For many years, it has been common to mount the backhoe support structure or swing tower on a frame and utilize a pair of hydraulic cylinders to pivot the tower with respect to the frame. In such a unit, the hydraulic cylinders are usually connected to the boom support or swing tower on opposite sides of the vertical pivot axis between the swing tower and the frame. For example, in one type disclosed in Long U.S. Pat. No. 3,047,171, the free ends of the piston rods of the hydraulic cylinders are connected to the frame structure at spaced locations while the cylinder barrels are connected at transversely spaced points to the swing tower or mast.
In more recent years, an earth-working vehicle of the type disclosed in the Long patent has also been mounted in a manner that the entire unit can be shifted transversely with respect to the vehicle. The frame supporting the mast or tower is supported on transversely extending rails that are secured to the rear end of the vehicle. This allows the operator to position the frame in any one of an infinite number of positions with respect to the fixed rails and readily lock the unit with respect to the rails.
A side-shaft backhoe incorporates a frame which supports the backhoe mechanism and which is mounted for lateral, transverse movement with respect to the tractor or the like on which the backhoe is mounted. This type of backhoe was developed primarily for trenching in confined spaces, such as in close proximity to a house or other obstruction and enables operation closer to the obstructions than if the backhoe were mounted centrally of the rear of the tractor.
Traditionally, an implement bucket has been repositioned by uncontrolled movement of the backhoe while supporting the backhoe bucket teeth on the ground to one side and pushing the slide carrying the backhoe out on the other side using hydraulic cylinders. Some of the side-shift backhoes required complex components including hydraulically or manually operated clamps or pins.